The present invention relates to a traction and alignment arm particularly for motor vehicle body repair benches.
Conventional special repair benches are used to repair the body of motor vehicles damaged by accidents; the damaged body is placed on these benches and fixed thereto. The body is then repaired by applying forces, generally traction forces, to the portions damaged by impacts during the accident, so as to return the body as much as possible to its original configuration.
Traction is generally applied to the damaged body portions by means of traction arms which are in most instances constituted by a usually tree-shaped horizontal base which is associable with the repair bench by means of one of its longitudinal ends and supports, at its other longitudinal end, a post which is pivoted to the base and connected to the portions of the part to be repaired that are to be subjected to traction by means of cables, chains or the like. Traction is applied to these cables or chains by means of a fluid-actuated cylinder pivoted to the base of the arm: the end of the stem of the piston of said cylinder acts on the post so as to increase the angle formed by the post and by the base of the traction arm.
In other traction arms, the fluid-actuated cylinder, instead of being interposed between the base and the post, is mounted on the post and acts directly on the chain or cable to apply traction to it. In this last type of arm, the post is generally rigidly associated with the base of the supporting arm instead of being articulated thereto.
In order to vary the direction of the force applied to the body portion to be repaired by means of the cables or chains, the base is associated with the bench by means of two supports: a first one can be rigidly fixed to the bench, whereas the second one is articulated to the first support so as to be rotatable along an arc of preset breadth about a vertical axis and in turn supports the base of the arm so as to be rotatable about a horizontal axis. In this manner it is possible to vary the orientation of the base with respect to the front plane where the traction arm is applied to the repair bench by rotating the base and the second support about the vertical axis, and it is furthermore possible to vary the inclination of the post with respect to a horizontal plane by virtue of the fact that the base is rotatable about its axis with respect to the second support.
Also known from FR-A-2102094 is a traction arm as defined in the preamble of claim 1.
Currently commercially available traction arms can furthermore be rigidly coupled to the bench both along the lateral sides and along the front sides, and the point where the chains or cables are applied to the post can be shifted along the extension of said post so as to allow further variations in the direction of the traction forces applied to the damaged body.
Nevertheless, currently commercially available traction arms are very often unusable, or usable with only partially satisfactory results, in certain repair situations, mainly due to the limitations that in any case occur in the possibility of orientating said arm and therefore the traction forces applied to the damaged regions of the body.
In particular, with currently commercially available traction arms it is extremely difficult to reach the upper and lower regions of the body and apply traction thereto with a correctly orientated force.